This book presents a system study on the theory, methodology, and architecture for Non-GPS based wireless positioning systems. The findings and detailed formulae can benefit researchers, postgraduate students and engineers. Of particular interest is the Weighted Least Squares Method (WLSM) for multi-antenna based positioning systems. It is well known that the performance of triangulation based positioning methods deteriorates rapidly when the impinging signal approaches the antenna planes. To overcome this difficulty, we have developed a weighting matrix which is derived from the angle of incidence of each antenna. The WLSM is shown to over-perform other methods significantly. To take advantage of the proliferation of low cost wireless ranging devices, a ranging based sensor array is presented. A closed form expression of the Standard Deviation (STD) is given and proved to reach the Cramér-Rao lower bound (CRLB). The CRLB for co-operative sensor arrays, for 2D and 3D cases, are all derived respectively. Finally, the book shed light on some of the promising directions for future research.